The present invention is directed to a mounting apparatus for electrical connectors and more specifically to a mounting apparatus providing a grounding path between the electrical connector and a chassis for electro-magnetic interference shielding.
RS232 electrical connectors are widely used in the electronic industry as hardware interfaces for connecting various types of electronic equipment. In particular, D-type subminiature RS232 connectors are used as serial ports in computers, display terminals, workstations, and the like. One type of D-type subminiature connector has an electrically conductive base and a raised connector portion containing male or female electrical contacts, which mate with opposite type contacts in a corresponding connector. Generally, a connector of this type is inserted into an opening in the electronic equipment chassis and secured to the chassis by screw, lock washer, and nut assemblies on each side of the raised connector portion. Pins connected to the electrical contacts and extending from the opposite side of the raised connector portion are soldered to a circuit board containing electronic circuitry and a ground plane. Electrically conductive brackets connected to the base of the electrical connector on the same side as the pins provide electrical continuity between the base and the circuit board ground plane, which is in electrical contact with the chassis.
Attempts have been made to eliminate the tedious and time-consuming task of securing these type of electrical connectors into chassis openings. One such prior art device consists of a molded plastic housing having a spring steel clip affixed thereto. The housing is screwed to the base of the electrical connector adjacent to each end of the raised connector portion. The housing has shouldered extensions adjacent to its base that are captured between the base of the electrical connector and the frame providing a firm seat for the connector. The spring steel clip is swedged into a depression formed in the top of the housing and has a portion extending outward from and bent downward toward the base of the electrical connector. The portion of the clip extending outward from the base has a shoulder formed therein that engages and secures the electrical connector in the chassis frame as the electrical connector is inserted into the opening. One drawback to this type of design is that the spring steel clips have to be depressed by hand or with a tool to disengage the shoulder from the chassis frame. A further and more serious drawback of this design is that the shouldered extensions on the housing prevents the base of the electrical connector from contacting the frame causing a loss of electrical continuity there between permitting conducted or radiated electro-magnetic interference (EMI) to occur.
To reduce EMI problems at a connector interface, the largest conductive surface area possible is used for grounding the connector to the chassis and the ground plane of the circuit board. For a D-type subminiature connector, the electrically conductive metal base provides a good grounding surface between the chassis and the connector. Metal brackets connect the base of the connector to the ground plane of the circuit board. In addition, an electrically conductive shell, generally of metal, surrounds the raised connector portion of the connector. In mating two D-type subminiature connectors together, the metal shell of one connector slidably engages the other shell. Various methods have been used to maintain the electrical continuity between the two connector shells. One method has been to provide outward protruding dimples on the mating surfaces of the shells. Another method, as exemplified in the D*U series socket connector marketed by ITT-Cannon, provides grounding springs mounted on the sides of the inner mating metal shell. The grounding springs are in the form of individual metal fingers that are depressed and captured between the mating connector shells. The above described grounding methods are directed to maintaining electrical continuity between two mating electrical connectors and not to maintaining electrical continuity between an electrical connector and a chassis frame.
What is needed is a fastening apparatus that can quickly and easily secure an electrical connector into a frame opening in an electrical chassis while at the same time providing good electrical continuity between the electrical connector and the frame preventing electro-magnetic interference problems.